Indexing tabbed filing guides may be used with file folders or, later on, can be folded to form file folders; they usually have projecting tabs with index markers thereon, for example the letters of the alphabet, numbers, or blank tabs for later application of adhesive strips with suitable identification of contents, or they may carry symbols or other recognition markers.
The tabs are stressed mechanically since they extend laterally from a stack of filing guides. To open the specific file, it is customary to grasp the file or guide at the tab. To prevent soiling, and to ensure integrity of the tab, it is necessary to reinforce the material in the region of the tab. The reinforcement should cover the tab and adjacent regions of the file guide, to protect the entire file guide against premature destruction and against damage. The reinforcements are applied by a machine to the file guides.